Introduction: Ectopic breast tissue in the axilla is a rare abnormality and there is currently not a single procedure accepted as standard treatment. The aim of this study was to describe the association between symptoms of ectopic breast tissue and choice of treatment, and related complications.

Methods: A retrospective study of patients diagnosed with ectopic breast tissue at Rigshospitalet, Denmark, in 2010-2013 was performed. Data was collected from original patient files to describe symptoms, treatment, hospitalisation, and complications. Fischer’s exact test was used to examine differences in symptoms between patients treated with surgery or conservatively.

Results: 85 patients were included in the study. The most common symptoms were a solid lump or swelling (67%). Of the 85 patients, 43 were treated conservatively (51%) and 42 with surgical excision (49%). Significantly more patients in the surgery group presented symptoms of cosmetic nuisance (p=0.03). More than half of the patients treated with surgical excision (57%) experienced complications, the most prevalent being seroma (24%) and paraesthesia (17%).

Conclusion: In our study, we found a high risk of complications after surgical excision of ectopic breast tissue in the axilla. Until further evidence exists, conservative treatment should be encouraged and surgical treatment should be balanced against the quality of life for the patient if conservative treatment is chosen.